Impulse conveyors move rigid conveyor surfaces or “trays” back and forth to incrementally move parts, scrap, and other small items (hereafter parts) forwardly along their length, typically using a speed differential with a slower forward pulse and a faster return pulse. The parts are carried forward by traction with the tray on the slower forward pulse and maintain their forward gain during the return pulse when the tray slides quickly back beneath them.
Examples of such conveyors include those shown in U.S. Pat. No. 6,371,282 to Brodin for a vibrating conveyor with a conveying plate moved back and forth by a horizontal, multi-lobed cam wheel and a pressure spring; and, Canadian Patent CA 2313777 A1 to Tamlin (Mayfran International) for a conveyor drive using a cam driving block or link to impart a reciprocating motion to the tray through a crank shaft with a varying rate of rotation.
U.S. Pat. No. 6,880,693 to Trestain teaches a differential impulse conveyor with a pneumatic conveyor motor, specifically an opposed air bellows motor with a linear motion capable of reciprocating multiple conveyor trays connected through an elongated crossbar. This pneumatic drive motor has proven to be commercially useful, but the present inventor has sought ways to eliminate the damaging effects of leverage force and conveyance inefficiencies caused by offset conveyor trays mounted to a linear motion drive system.